1. Field of the Invention
The present invention relates to optical printing systems and, more particularly, to a line-scanning optical printing system comprising a spatial light modulator configured to produce printed images without generating linear artifacts.
2. Description of the Prior Art
Conventional optical printers typically utilize an optical radiation source emitting one or more beams of visible, ultra-violet, or infra-red radiation which may be modulated by means of a spatial light modulator (SLM) before being projected onto a radiation-sensitive medium. In such printers, the SLM is used to produce sequential portions of the desired image on the medium, typically line-by-line, as the medium is scanned or translated relative to the beam of optical radiation. For color images, the optical radiation may be provided by means of colored light sources, such as light emitting diodes (LEDs), or by means of a polychrome light source in combination with color filters.
In many applications, the SLM comprises a linear array of liquid-crystal device (LCD) shutters or cells. Any cell in the SLM can be addressed to change its transmissiveness so as to transmit some or all of the incident radiation to form an individual pixel in the image, the transmitted portion being projected onto the radiation-sensitive medium. Because of the characteristics of LED radiation sources and the transmissive geometry of conventional LCD cells, there often results linear artifacts in the printed image. These linear artifacts may take the form of dark lines extending both parallel to and orthogonal to the direction of scanning.
Accordingly, it is an object of this invention to provide an SLM configured so as to minimize or eliminate the generation of linear artifacts in a printed image. Other objects of the invention will be obvious, in part, and, in part, will become apparent when reading the detailed description to follow.